This invention relates to a gasket for magnetic tape packages, known as "cassettes", as employed in tape recorders, players, and the like apparatus.
As is known, magnetic tape playing or recording cassettes include a case, wherein the tape is wound around two pins, thus forming two coils. The coils do not contact directly, with their edge portions, the inner surfaces of the case, but are arranged to contact gaskets, which are substantially plastics material sheet gaskets shaped to fit the case contour. These gaskets have a basic feature in common: their faces contacting the magnetic tape have a graphite coated surface, or surface coated with an equivalent lubricating material. Thus, the gaskets serve the function of a bearing between the tape and case which improves the sliding of the magnetic tape.
Such gaskets are necessary to the proper operation of a cassette, but have the disadvantage of increasing the cost of the cassettes. Therefore, the present trend is towards the maximum simplification and rationalization of the gasket structure in order to reduce the cost thereof with least prejudice for their functionality.
In particular, the trend is towards a standardized shape of the gaskets, to fit cassettes of any shape, as well as, and above all, a reduction to the least possible amount of the graphite or equivalent material. In fact, solutions have been proposed where the central strip of the gaskets is left free of graphite which comprises the bores for the pins, or where the graphite is laid grate-like on the gasket. Thus, the use of graphite is effectively reduced with respect to fully coated gaskets, although a considerable amount of graphite is still used, and above all, this graphite can remain unusued if the cassette case happen to be imperfectly true or flat, or if the coil has been irregularly coiled, thereby it cannot contact the graphite-coated surface evenly.